This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Exercise capacity is extremely low in patients with end stage renal disease (ESRD) treated with conventional hemodialysis and improves significantly shortly after transplantation. It is suspected that factors associated with uremia impair the normal integration of physiological systems required for increased oxygen transport and utilizatoin during exercise. There is growing interest in slow daily hemodialysis (both short daily hemodialysis and slow nocturnal hemodialysis), which increases the dialysis provided and reduces uremic signs and symptoms. We propose to study patients with ESRD treated with 4 different modalities: conventional hemodialysis (CHD) (3 days/week, 3-4 hours/treatment), slow nocturnal hemodialysis (SND) (8 hours/treatment, 6 night/week), short daily dialysis (SDD) (2 hours/treatment, 6 days/week) and living donor transplantation (RTX) to assess differences in physiological responses to and determinants of exercise.